1. Article purpose[edit source]
The purpose of this article is to explain how to monitor the HSE oscillator.
If the HSE oscillator is used in the clock tree, it is possible to enable a monitoring function to detect and avoid over frequency. The LPTIM mechanism can detect any over frequency and triggers a tamper event which runs the appropriate custom actions.
2. How to activate the monitoring[edit source]
By default, the HSE monitor is disabled in the dtsi "SoC" files.
To activate the HSE monitor, add this node in your board OP-TEE device tree
&hse_monitor {
status = "okay";
};